What volume of hcl solution of density 1.2g/cm3 and containing 36.5% by weight hcl, must be allowed to react with zinc in order to liberate 4g of hydrogen

The answer 333.3ml

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To find the volume of HCl solution needed to liberate 4g of hydrogen, we can use stoichiometry and the molar mass of hydrogen (H2). The balanced chemical equation for the reaction between zinc (Zn) and hydrochloric acid (HCl) is as follows:

Zn + 2HCl → ZnCl2 + H2

Here are the steps to find the volume of HCl solution needed:

Step 1: Calculate the moles of hydrogen gas (H2) based on the given mass (4g) and the molar mass of hydrogen (2.02g/mol).

Moles of H2 = Mass of H2 / Molar mass of H2
Moles of H2 = 4g / 2.02g/mol
Moles of H2 = 1.98 mol (approximately)

Step 2: Use the balanced equation to relate the moles of hydrogen gas to the moles of hydrochloric acid. From the balanced equation, we know that 1 mole of hydrogen gas is produced for every 2 moles of hydrochloric acid.

Moles of HCl = 2 × Moles of H2
Moles of HCl = 2 × 1.98 mol
Moles of HCl = 3.96 mol (approximately)

Step 3: Convert the moles of hydrochloric acid (HCl) to grams using its molar mass (36.46g/mol). This will give us the mass of HCl needed.

Mass of HCl = Moles of HCl × Molar mass of HCl
Mass of HCl = 3.96 mol × 36.46g/mol
Mass of HCl = 144.62 g (approximately)

Step 4: Use the density of the HCl solution (1.2g/cm^3) and the mass of HCl calculated in the previous step to find the volume of HCl solution needed.

Volume of HCl solution = Mass of HCl / Density of HCl solution
Volume of HCl solution = 144.62 g / 1.2 g/cm^3
Volume of HCl solution = 120.52 cm^3

To convert the volume from cm^3 to mL, we know that 1 cm^3 is equal to 1 mL. Therefore:

Volume of HCl solution = 120.52 mL

Rounding to three significant figures, the volume of HCl solution needed to liberate 4g of hydrogen is approximately 120.5 mL, not 333.3 mL as mentioned in the initial answer.

To find the volume of HCl solution needed, we can use the following steps:

Step 1: Determine the molar mass of HCl.
- The molar mass of HCl (hydrochloric acid) is the sum of the atomic masses of hydrogen (H) and chlorine (Cl).
- The atomic mass of hydrogen (H) is approximately 1 gram/mol.
- The atomic mass of chlorine (Cl) is approximately 35.5 grams/mol.
- Thus, the molar mass of HCl is 1 + 35.5 = 36.5 grams/mol.

Step 2: Calculate the moles of hydrogen gas (H2) required to liberate 4 grams of hydrogen.
- Hydrogen gas (H2) is liberated when 2 moles of HCl react with zinc.
- Since 2 moles of HCl produce 1 mole of H2, we need to calculate the moles of HCl.
- The molar mass of HCl is 36.5 grams/mol, so the number of moles is given by:
Moles of HCl = Mass of HCl / Molar mass of HCl.
- Since we have 4 grams of hydrogen, the mass of HCl needed is 4 grams.
- Therefore, the moles of HCl required is 4 / 36.5 = 0.109 moles.

Step 3: Convert moles of HCl to volume using the density of the solution.
- The density of the HCl solution is given as 1.2 g/cm3.
- Density is defined as mass per unit volume.
- The equation to calculate volume is:
Volume = Mass / Density.
- Since we know the mass (4 grams) and the density (1.2 g/cm3), we can calculate the volume.

Let's calculate the volume using the steps:

Volume = Mass / Density
= 4 grams / 1.2 g/cm3
= 3.333 cm3.

Since the given answer is in milliliters (ml), we can convert cm3 to ml by noting that 1 cm3 is equal to 1 ml.

Therefore, the volume required is 3.333 ml, which is approximately equal to 333.3 ml.

What is the molarity of the HCl solution? That's

1000 mL x 1.2 g/mL x 0.0365 x (1 mol/36.5g) = 12M

Zn + 2HCl ==> ZnCl2 + H2
How many mols is 4g H2.
mol = grams/molar mass = 4/2 = 2
2 mols H2 = 2*2 = 4mols HCl

M HCl = mols HCl/L HCl. You know M HCl from above and mols HCl from above, solve for L HCl and convert to mL.